NL8003241A - CELLULOSE-ETHER AND METHOD FOR THE PRODUCTION THEREOF. - Google Patents

Description

ti r -1- 21282 / Vk / mv **

Applicant: Hercules Incorporated, Wilmington, Delaware, United

States of America.

Short designation: Cellulose ether and method for its preparation.

The invention relates to cellulose ethers with a sufficient degree of non-ionic substitution. The invention further relates to a method of preparing such cellulose ethers.

In particular, the invention relates to a new type of modified water-soluble polymers. In particular, these are polymers that have been modified to such a state that they are no longer water soluble but retain their solubility and have suitable properties in detergent systems.

Nonionic water-soluble cellulose ethers are used in a wide variety of applications where viscosity influencing agents are desired. These are widely used as a thickener, as a water retention aid and as a suspension aid in certain polymerizations. For other purposes, specific cellulose ethers are required, but for a number of methods, various ethers can be used depending on cost and in many cases simply at the user's choice. Widely used are the commercially available non-ionic cellulose ethers including methyl cellulose, hydroxypropylmethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and ethyl hydroxyethyl cellulose.

As is generally the case with high polymers, better thickening and viscosity-determining effectiveness can be obtained with higher molecular weight cellulose ethers,

The preparation of very high molecular weight substances requires the use of very expensive cellulosic end substances such as cotton ribbons (linters) instead of the more commonly used wood pulp. Moreover, it can be stated that even with the use of high molecular substances, the ether formation is very stiff in the preparation and effects a significant reduction of the molecular weight of the cellulose. High viscosity solutions are then very difficult to obtain without affecting subsequent steps such as cross-linking. This is not a practical alternative with 800 32 41 -2- 21282 / Vk / mv non-ionic cellulosic materials because good cross-linking is not known and they are often very difficult and inefficient to perform. The other way known so far to achieve a high viscosity is to use the polymer in a high concentration. This technique is often inefficient, impractical or not desirable for any other reason.

U.S. Patent Application 11,613 (filed Feb. 12, §79) discloses a water-soluble cellulose ether having a greatly increased viscosity, compared to the known water-soluble cellulosic elevations of comparable molecular weight, which are nonionic cellulose ethers which have been further modified by substitution with specific amounts of alkyl radicals of 10-16 carbon atoms. Such ethers are substituted with an amount of a long chain alkyl radical to the amount that they are water insoluble. * The thickening or viscosity determining properties of these ethers on an aqueous system is increased even further in the presence of nonionic surfactants, although at higher levels of the modification these are insoluble in such aqueous systems when such surfactants are present.

The studies conducted have yielded a class of non-ionic cellulose ethers modified with alkyl radicals of 10-24 carbon atoms, which have been found to be insoluble in water, but soluble in surfactant and surfactant systems fabrics themselves.

The cellulose ethers of the present invention are low to medium molecular weight cellulose ethers with a sufficient degree of non-ionic substitution selected from radicals, characterized in that they are methyl hydroxyethyl and hydropropyl radicals so that they are normally 30 times soluble. in water and further substituted with a hydrocarbon radical of 10-24 carbon atoms in an amount such that it is between the amount which makes the ether insoluble in water and about 8% by weight based on the total weight of the modified cellulose ethers . The cellulose ether is then substituted to be insoluble in water, but less than 8% by weight based on the total weight of the modified cellulose ether.

Preferably, the cellulose ether for the modification is such that it has a molecular weight of less than about 20,000-500,000 800 32 41 -1-3-2828 / Vk / mv * (a degree of polymerization of 75-1800) and more particularly between about 20,000 and 80,000 (degree of polymerization 75-300).

Thus, cellulose ethers are obtained with an amount of hydroxypropyl, hydroxyethyl or methyl radicals that they are normally water-soluble and are further modified with hydrocarbons of 12-24 carbon atoms so that they are insoluble in water. These modified ethers are soluble in surfactants and have a significant effect on increasing the viscosity in the surfactant solution. They are also very effective as an emulsifying agent in aqueous systems.

Cellulose ethers have hitherto been modified with small hydrophobic groups such as ethyl, butyl, benzyl and phenylhydroxyethyl groups. Such modifications or such modified products are disclosed in U.S. Pat. Nos. 3,091,542-15 3,272,640 and 3,435,027. These modifications are usually accomplished with the aim of decreasing hydrophilicity and thus decreasing the degree of hydration of the cellulose ether. These modifiers have been found to have no effect on improving the properties brought about by the modifications of this invention.

This means that there is no significant change in the rheological properties on the surfactants of the ethers. Another modification of water-soluble cellulose derivatives is disclosed in U.S. Pat. Nos. 3,824,085 and 3,960,514. These patents describe hydroxypropyl cellulose laurate and its use.

25 as a hydrocarbon with a gelling effect. The degree of substitution of these products is quite high, and they are neither water-soluble nor capable of affecting the viscosity of the aqueous systems.

Any nonionic water-soluble cellulose ether can be used as a cellulose ether substrate to form the products of the invention. Thus, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, hydropropyl methyl cellulose, ethyl hydroxyethyl cellulose and methyl hydroxyethyl cellulose can be modified.

The amount of nonionic substituents such as methyl, hydroxyethyl, or hydroxypropyl does not appear to be critical as long as they are present in an amount sufficient to cause the ether to be initially water soluble.

The modified cellulose ethers of the invention have been identified as water-insoluble substances. The modified cellulose ethers of the present invention have been identified as being water insoluble. 800 32 41 -4- 21282 / Vk / mv. In the context of the invention soluble in water means that the insolubility is less than 1% by weight or that a swollen gel is obtained at more than 1% concentration in water. Substances with greater water solubility are often insoluble in surfactant systems and form cloudy or cloud-like mixtures.

The content of modifier (wt%) is determined using a modified Zeisel method. The ether-bound hydrophobic is cleaved using 35% HBr in acetic acid. The brominated hydrocarbon reaction product is extracted with hexane and analyzed via a temperature programmed flame ionization.

The weight percent of the modifier 15 in which the cellulose ether is insoluble in water is mainly influenced by the size of the long alkyl chain modifier and to a lesser extent by the molecular weight and hydrophilicity of the cellulose ether substrate. The amount of modifier is best expressed in terms of the average number of modifying units per polymer chain. It has been experimentally determined that for all nonionic water-soluble cellulose ethers, the relationship between the amount resulting in insolubility and the number of carbon atoms ( Cn) of the modifier is determined by the equation log N ^ g = K - 0.07 + 0.005 Cn.

The constant K ranges from 1.4 to 2.1 and is a function of the hydrophilicity of the cellulose ether substrate. K has a value of about 1.5 to 1.8 for methyl cellulose, about 1.9 to 2.2 for hydroxyethyl cellulose and hydroxypropylmethyl cellulose.

In general, N-g ranges from about 1 to 25.

The limits can be calculated using the overall limits of any water-soluble cellulose ether that can be used according to the invention. Thus, for methyl cellulose (K = 1.8), Njns is about 13 when a hydrocarbon modifier with 35 carbon atoms is used and about 3 when the modifier has 20 carbon atoms. N - g for hydroxyethyl cellulose with a medium degree of polymerization is about 25 with a 10 carbon atoms hydrocarbon modifier and about 5 with an 800 carbon 2 21-252 / Vk / rav modifier with 20 carbon atoms.

The solubility in surfactants is observed in an aqueous solution thereof of about 5 wt.% Concentration of the surfactant and above, preferably 5-40 wt. % aqueous solution of the surfactant. The limits of the concentration of modified cellulose ether in the surfactant solution are related to the surfactant concentration. Generally, the solubility appears to require a surfactant to cellulose ether ratio of at least about 5 to 1.

The modified cellulose ethers. : Are soluble in all water-soluble surfactants and aqueous solutions. These are soluble in all nonionic cationic, anionic and amphoteric surfactants with a water solubility greater than 5g per 100g water.

Examples of surfactants that can be used within the various types are the fatty acids of sorbitan, ethoxylated or propoxylated sorbitan esters, ethylene and propylene glycol fatty acid ester, monoesters of glycerine, polyoxyethylene-derivatives of glycerine, polyoxyethylene derivatives of .lanoline, polyoxyethylene of resin acids, alkyl and aryl sulfonates, triethanolamine fatty acid ester and its salts, alkali metal lauryl sulfonates, long chain alkyl quaternary salts and alkali metal salts of unsaturated fatty acids.

The long chain alkyl modifiers can be coupled to the cellulose ether substrate via an ether, ester or urethane bond. Preferably, the ether bond is most commonly used as the ether formation reagent which is readily obtainable, which reaction is equal to that of the reaction usually used for the initial ether formation and the reagents are usually more readily used than the reagents used for the modification through the other bonds. The resulting bond is usually also more resistant to further reactions.

Methods of preparing the mixed ethers of cellulose, i.e., the products having more than one ether modifier coupled to the same cellulose molecule are known per se.

The products of the invention can be prepared by essentially the same method. Briefly, it can be stated that 800 32 41 S -6- 21282 / Vk / rav the bi.i preferred method of preparing the mixed ethers of the invention is slurry formation of the nonionic cellulose ether in a inert organic diluent such as a lower aliphatic alcohol, ketone or hydrocarbon and adding a solution of an alkali metal hydroxide to the resulting slurry at a low temperature. When the ether is well wetted and swelled by the alkaline, a 10-24 carbon halide, preferably a bromide, is added and the reaction is continued with stirring until complete. The remaining alkaline is then neutralized and the product is recovered, washed with inert diluents and dried. Ether formation can also be accomplished with an epoxide having 10-24 carbon atoms or halohydride, but these are sometimes less reactive and less efficient.

The same preferred method is mainly used to couple the hydrocarbon modifying agent via the ester or urethane bond. Conventional slurry methods for reacting this type of modifying agent with cellulose ethers, i.e. without the alkaline, are ineffective. The alkali syrup is required to ensure that the cellulose ether is swollen at the time when the modifier can react substantially homogeneously to all cellulose ether molecules. If the reaction does not proceed substantially homogeneously over the entire cellulose ether mass, the improved rheological properties are not achieved.

Although the products of the invention have been designated as a modified long chain alkyl group, it will be understood that except for the case where the modification is effected with an alkyl halide, the modifier is not simply a long chain alkyl group. In particular, the group is a Q (hydroxyalkyl radical when an epoxide is used, a urethan radical in the case of an isocyanate or an acyl radical with an acid or acyl chloride. However, the term "long chain alkyl group" is used because the size and influence of the hydrocarbon portion of the modifying molecule substantially overshadows any detectable influence of the linking group 35. The properties are not significantly different from that of the product modified with a simple long chain alkyl group.

The invention is further elucidated on the basis of 800 3 2 41% -7- 21282 / Vk / mv the following examples.

Example I

A slurry of 80 wt. parts of hydroxyethyl cellulose of medium viscosity (2.5 M.S.) in 393 parts of isopropanol 5 were prepared and degassed by nitrogen spit. To this were added 72 parts of an aqueous solution of 35.5% NaOH. This solution was stirred at a temperature of 0-5 ° C under a nitrogen atmosphere. After about 16 hours, 45 parts of 16-carbon epoxide was added to the slurry. The temperature was raised to 75 ° C and the reaction was continued continuously for 6 hours.

The reaction mass was neutralized with HNO 2 and the pH adjusted to 7 with acetic acid. The product was separated by filtration and washed with 330 parts of hexane. Hexane was removed and the modified polymer was dissolved in methanol / 15 water is 80/20. The polymer was precipitated with acetone, separated from the liquid and washed with acetone until hard enough to be filtered off, then dried at room temperature overnight.

The modified product contained 2.68% modification -20 agent with 16 carbon atoms and was less than 1% soluble in water.

Example II

Low viscosity hydroxyethyl cellulose was reacted as indicated in Example I except that only 23 parts of the 16-carbon epoxide was used. The modified product contained 6.3% modifier with 16 carbon atoms and was less than 1.3%. soluble in water.

Example III

A slurry of 80 parts by weight of low viscosity hydroxyethyl cellulose 30 in isopropanol was prepared and degassed by nitrogen spit. 72 parts of solution of 35.5% NaOH were added to this. This mixture was stirred for about 16 hours at a temperature of 0-5 ° C during which time 45 parts of 16 carbon atom epoxide was added and the temperature was raised to 75 ° C for 3.5 hours. The reaction mixture was neutralized with nitric acid and the pH adjusted to about 7 with acetic acid.

The polymer was removed from the isopropanol reaction medium and washed several times with hexane. After removing hexane, 800 3 2 41 Μ -8-21282 / Vk / mv the polymer was dissolved in methanol / water (90/10) and the polymer was precipitated with hexane. Hexane was removed by decantation and the polymer was washed with acetone until it had hardened enough to be filtered under charged pressure. The remaining acetone was removed by drying the polymer overnight under reduced pressure at room temperature. The modified polymer contained 3.05% modifier with 16 carbon atoms and was less than 1% soluble in water.

Example IV

A solution of 10 g of low molecular weight hydroxyethyl cellulose (2.5 M.S.) in 190 g of distilled dimethyl sulfoxide (DMS0) was vented with nitrogen to remove oxygen. To this was added 0.9 kal of potassium t-butoxide in 15 ml of distilled DMSO.

A dispersion of 0.4 g of 16-carbon epoxide in 5 ml of DMSO was added quickly with stirring to the reaction mixture at room temperature. The temperature was raised to 80 ° C for 40 minutes and held at this temperature for 3 hours. At the end of the reaction period, the mass had the appearance of a thick gel. This was cooled to room temperature and left overnight.

Acetone was added to the reaction mixture and ground in a closed mixer. This step was repeated three times removing acetone by decantation after each milling operation. Finally, the solid was added to a large volume of acetone ai with a "Cowles" blade stirred for 30 minutes, then recovered by suction filtration and air-dried. The modified ether contained 3.5 wt. % of the modifier with 16 carbon atoms ai was less than 1% soluble in water.

Example V

The procedure outlined in Example IV was repeated using 2 g of 16 carbon epoxide to prepare a modified product with about 5.8% modifier

Example VI

A slurry of 80 wt. parts of low viscosity hydroxyethyl cellulose in 393 parts of isopropanol was prepared and guest 800 3 2 41-921282 / Vk / mv by nitrogen spit. To this were added 72 parts of 35.5% sewer aqueous solution and NaOH solution. This mixture was stirred at 0-5 ° C for 16 hours. 36 g of the 12-carbon epoxide was added. The temperature was raised to about 70-75 ° C and the reaction continued for 3.5 hours with constant stirring under an argon blanket. The reaction mass was cooled to room temperature and neutralized to a pH of about 7 with nitric acid and then with acetic acid. After removing the polymer from isopropanol, it was washed 2 times with hexane, then 2 times with 20% aqueous acetone and then dried under reduced pressure at room temperature. The modified polymer contained 2.42% modifier with 12 carbon atoms ai was less than 1% soluble in water.

Example VII

The procedure set forth in Example 6 was repeated except that the reaction was run for 4.5 hours. The water-insoluble product contained 3.4% modifier with 12 carbon atoms.

Example VIII

The procedure indicated in Example VI was repeated using an epoxide with 14 carbon atoms, the reaction being continued for 3.5 hours. The water-insoluble product contained 2.44% modifier with 14 carbon atoms.

Example IX

Example VIII was repeated using a reaction time of 5 hours. The water-insoluble product contained 2.75% modifier with 14 carbon atoms.

The solubility of the modified cellulose ethers of the invention make them suitable as agents for adjusting viscosity for shampoo compositions where many conventional water-soluble gums cannot be used. The current trend with regard to the shampoos is to prepare them with a low pH with substances that have a low irritation to the eyes. This has made it necessary to remove from the compositions the salts and amides which have hitherto been used as viscosity controlled components. The intolerance of the conventional gums such as, for example, hydroxethyl cellulose makes this composition particularly difficult to use to control viscosity.

. 800 3 2 41 -10- 21282 / Vk / rav ar

The modified cellulose ethers of the present invention are compatible with surfactants at the concentrations used in most shampoos and effect a significant viscosity increase. In most cases the compositions are crystal clear solutions.

Example X.

Low molecular weight hydroxypropyl cellulose was dissolved in 90% isopropanol with NaOH (1.5 N) and a hydrophobic epoxide. The thick solution was stirred for various time periods as indicated in Table A at a temperature of 75 ° C. The product was separated by precipitation in hexane. All products in Table A are insoluble in water, but readily soluble in a 10% solution of sodium tetradecyl sulfate in water.

15 TABLE A

example number of amount of time modification (wt%) carbonity (g) (urai) atoms of the epoxide

Xa 12 20 3 1.02

Xb 14 20 3.75 1.13

Xc 20-24 20 4 1.43

Xd 16 20 3 0.93 25 Xe 14 36 3.5 1.90

Xf 20-24 40 3.5 2.75

Example XI

Methylhydroxypropylcellulose (Meteeleel A4C - Dow) was modified by reswelling in an isopropanol slurry, with caustic at 75 ° C for certain times with hydrophobic epoxide contents as listed in Table B. All products are water insoluble as listed in Table B but easily dissolve in a 10% solution of sodium tetradecyl sulfate.

800 32 41 s -11- 21282 / Vk / mv

TABLE B

example number of coal amount of time modification (wt%) 5 substance atoms in (g) (hours) of the epoxide

Xla 12 36 5.5 2.90

Xlb 14 36 5.5 2.60 XIc 20-24 36 5.5 2.60 10__

Example XII

Example XI was repeated, however using hydroxypropethyl ethyl cellulose (Methocel E-50 Dow) in place of methyl cellulose. All samples were water insoluble but soluble in 10% sodium tetradecyl sulfate.

TABLE C

20__ example number of coal amount of time modification (wt%) dust atoms in (g) (hours) the epoxide

Xlla 12 36 3.5 2.80 25 Xllb 14 36 3.5 2.60 XIIc 15-18 36 3.5 2.10

Example XIII

A low pH shampoo composition consisted essentially of the following ingredients, with the shampoo composition being referred to Soap Cosmetics, amd Chemical Specialties, July 1978.

35 800 3 2 41 -12- 21282 / Vk / mv N-carboxymethyl-N- | (ó {-oxocarboxymethyl) -ethyl-2-dodecylimidazoline 12.0 parts lauryl sulfate triethanolamine 3.7 parts 5 laurin edi ethanolami de 5.0 parts and ethyl dimethyl (3-lanolin amide) ammonium phenyl sulfate 12.0 parts 10 water 22.3 parts propylene glycol 6.5 parts 15 cellulose ether dispersion 38.5 parts

The first four substances and the water were mixed under heating to 70 ° C for 4 minutes. The water-insoluble cellulose ethers that were tested were dispersed in water at a temperature of 70 ° C with stirring. The warm surfactant mixture was then added to the warm dispersion with stirring followed by propylene glycol. The mass was then stirred for a time from about 15 minutes to an hour until the polymer dissolved. The data obtained hereby are stated in thbel D.

25

TABLE D

modifier polymer concentration viscosity appearance 30 and concentration (%) tration in the (cps.) mixture (%) _.__ none - 56 clear hydroxyethylcellulose 2 - intolerant 35 C16 - 2.7 0.8 475 clear C1g 2, 7 1 3575 slightly cloudy 2.7 1.5 18000 cloudy 800 32 41 -13- 21282 / Vk / mv

X

TABLE D (Continued) modifier and polymer concentration viscosity appearance -5 concentration v (%) _ in the mixture (%) _ (cps.) Form_ C 3 2 925 clear 16 C ^ 6 - 6.3 · 2 1250 clear C14 - 2 , 4 2 335 clear C14 - 2.75 2 405 clear 10 C12 - 2.4 2 330 clear C12 - 3.4 2 365 clear

The solubility of the modified cellulose ether 15 in the surfactants and the significant viscosity increase achieved thereby are evident from the data in this table.

Despite the water insolubility, the novel cellulose ethers of the invention are themselves very effective agents for generating emulsions in aqueous systems. This is further demonstrated in Example XIV.

Example XIV

Mixtures of 50 parts of water with one part of hydroxyethyl cellulose modified with a 16-carbon hydrocarbon and 50 parts of a water-immiscible hydrocarbonaceous oil were prepared and well homogenized with a stirrer. Initially, all systems were completely dispersed when removed from the homogenizer. After one day, the unmodified hydroxy cellulose emulsion was separated as an oil phase. All of the modified hydroxy-30 ethyl cellulose emulsion did not give an oil phase separation although slight differences could be observed with regard to the degree of crane formation. Further details are listed in Table E.

35 800 3 2 41 t -14- 21282 / Vk / mv

TABLE E

no. oil molecular weight * C16 separation of oil fasc 5 polymer 1 fractol medium o yes 2 fractol low 0 yes 3 fractol medium 2.01 no 4 fractol medium 4.31 no 10 5 fractol medium 6.7 no 6 fractol low 3.1 no 7 Fractol layer 5.1 no 8 Xylene layer 0 yes 9 Xylene medium o yes 15 10 Xylene medium 2.01 no 11 Xylene medium 4.31 no 12 Xylene medium 6.7 no 13 Xylene layer 3.1 no 14 Xylene layer 5 , 1 no 20 15 pine oil low 0 yes 16 pine oil medium 0 yes 17 pine oil medium 2.01 no 18 pine oil medium 4.31 no 19 pine oil medium 6.7 no 25 20 pine oil low - 3.1 no 21 pine oil low 5, 1 no 30 - conclusions - 800 32 41

Claims (6)

1. Cellulose ether with a sufficient degree of nonionic substitution, characterized in that it is selected from methyl, hydroxyethyl and hydroxypropyl radicals so that it becomes normally soluble in water and is further substituted with a hydrocarbon radical of 10-24 carbon atoms in an amount such that it is between the amount of the water-insoluble ether and about 8% by weight, based on the total weight of the modified cellulose ether. Water insoluble cellulose ether according to claim 1, characterized in that the normally soluble cellulose ether for the modification has a degree of polymerization of about 75 to 1800. Cellulose ether according to claim 2, characterized in that the non-ionic substitution of the hydroxyethyl radicals is effected. Cellulose ether according to claim 2, characterized in that the non-ionic substitution of the hydroxypropyl radicals is effected. Cellulose ether according to claim 2, characterized in that the non-ionic substitution of the methyl radicals is effected. 6. Process for preparing a cellulose ether with a sufficient degree of non-ionic substitution, characterized in that the substitution is effected by methyl, hydroxyethyl and hydroxy-propyl radicals, so that the cellulose ether is normally soluble in water and further is substituted with a hydrocarbon radical of 10-24 carbon atoms in such an amount that it makes the ether insoluble in water and up to 8% by weight based on the total weight of the modified cellulose ether. Eindhoven, May 29, 1980. 800 32 41